The back-to-school season is upon us, and once again, parents across the country have loaded their kids’ backpacks up with snack packs and school supplies. It’s a good moment to reflect on what else we should be giving our kids as they head off to school.

American parents are feeling particularly anxious about that question this year. The educational process feels more than ever like a race, one that starts in pre-preschool and doesn’t end until your child is admitted to the perfect college. There is a lot of advice out there on how best to help our kids thrive, but after surveying the research, I believe that most parents are more worried than they need to be about their children’s grades, test scores and IQ. And what we don’t think about enough is how to help our children build their character — how to help them develop skills like perseverance, grit, optimism, conscientiousness, and self-control, which together arguably do more to determine success than S.A.T. scores or I.Q.

In fact, there’s growing evidence that our anxiety about our children’s school performance may actually be holding them back from learning some of these valuable skills. If you’re concerned solely with a child’s G.P.A., then you will likely choose to minimize the challenges that child faces in school. With real challenge comes the risk of real failure. And in an ultra-competitive academic environment, the idea of failure — even a small, temporary failure — can be very scary, to students and parents alike.

But experiencing failure and adversity, researchers have found, is a critical part of building character. Recent research by a team of psychologists led by Mark Seery of the University at Buffalo, State University of New York, found that adults who had experienced little or no adversity growing up were actually less happy and confident than those who had experienced a few significant setbacks in childhood. Overcoming those obstacles, the researchers hypothesized, “could teach effective coping skills, help engage social support networks, create a sense of mastery over past adversity, [and] foster beliefs in the ability to cope successfully in the future.”

By contrast, when we protect our children from every possible adversity — when we call their teachers to get an extension on a paper; when we intervene in the sandbox to make sure everyone is sharing their toys; when we urge them to choose only those subjects they’re good at — we are denying them those same character-building experiences. As the psychologists Madeline Levine and Dan Kindlon have written, that can lead to difficulties in adolescence and young adulthood, when overprotected young people finally confront real problems on their own and don’t know how to overcome them.

In the classroom and outside of it, American parents need to encourage children to take chances, to challenge themselves, to risk failure. Paradoxically enough, giving our kids room to fail may be one of the best ways we can help them succeed.